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Post NST: erratic or unresponsive touch-screen (and it's not caused by dirt)

OP marcoNST

13th May 2014, 03:46 AM   |  #1  
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Hello there,

I decided to post in here after doing extensive research online but having found no answer to my problem....

I have had a rooted (with NookManager) Nook Simple Touch that worked perfectly until I went travelling across tropical countries. Since then, I have seen a progressive degradation of the touchscreen, specifically I noted the following:
  • Buttons/icons in the lower half of the screen, when tapped, do no respond. Instead, buttons/icons directly above them (on the upper part of the screen) do respond to the action.
  • When the keyboard is active and letters are tapped, you get one of these random behaviours:
  1. the letter appears on the screen, but 2 or 3 of them, even if the letter is tapped once.
  2. the letter above the one tapped, appears on screen: e.g. I press "q" and "a" appears on screen; I press "backspace" and the letter "p" appears on screen.
Following the recommendations of many forums, I cleaned thoroughly my screen, however this does not seem to resolve the problem. I also performed a factory reset and re-root, still the problem persists (though, after a new factory reset, the erratic behaviour is less frequent, at start, but then It worsens as time goes by).

The only thing that changed is the fact that I am now travelling in hotter countries and maybe the Nook is sensitive to temperatures constantly above 30C. so I suspect it may be the cause.

Has anyone experienced similar problems?

Thanks

Marco
13th May 2014, 12:45 PM   |  #2  
Renate NST's Avatar
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The processing for the zForce touch screen is done by a TI MSP430 processor.
This is separate from the main OMAP 3621 processor.
They communicate over I2C.
There are no user-friendly diagnostics built in.
It's difficult to identify problems.

I have a unit with a similar problem.
I've been starting to look into this.
I'd like to make a user app that deals with the more common problem of dirt and would actually indicate where the dirt is.
(The problem with this unit is not dirt either.)
14th May 2014, 06:43 AM   |  #3  
Renate NST's Avatar
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I've got a new utility for debugging problems with the touch screen.
At the very least it should be able to tell you where the dirt is when it is dirt.
I need to do some polishing up on it.

The screenshot is a touchscreen with one touch in the middle.
The lines at the top and bottom are marginal performance of the edge sensors.
When there is no touch all the lines should be light gray.
The black indicates where it thinks there is an obstruction.
Last edited by Renate NST; 15th May 2014 at 09:35 AM.
14th May 2014, 07:22 PM   |  #4  
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Thanks so much for your response, Renate.
I very much look forward to your tool!

It is quite a frustrating behaviour that seriously limits the interaction with my NST (last time it took me 1 hour just to be able to type a wireless password correctly!).

Marco
Last edited by marcoNST; 15th May 2014 at 05:30 PM.
14th May 2014, 10:17 PM   |  #5  
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Here's an alpha version of the utility.
When you run it, most of the lines should be a light gray.
Touch some place and it will show black lines.
Paste a screenshot if you would please.

I may be hot on the track of what the actual problem is.
Questions:
  • Did this happen slowly over time?
  • Was it humid there or just hot?
Last edited by Renate NST; 15th May 2014 at 09:35 AM.
15th May 2014, 08:15 AM   |  #6  
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Quote:
Originally Posted by Renate NST

Questions:

  • Did this happen slowly over time?
  • Was it humid there or just hot?

Renate,

I'll try your utility later on today, after rooting again my net, and then let you know.
In the meanwhile, to answer your questions:

- yes, the problem started occasionally and worsened over time. Now, after 3 months from when I first appeared, I can hardly use the touchscreen
- it is hot and humid.
Last edited by marcoNST; 15th May 2014 at 05:30 PM.
15th May 2014, 09:39 AM   |  #7  
Renate NST's Avatar
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New alpha version.
  • Light line - open pathway working correctly
  • Dark line - blocked pathway
  • Dashed line - maxed out LED drive, something not optimal
Last edited by Renate NST; 15th May 2014 at 03:43 PM.
The Following User Says Thank You to Renate NST For This Useful Post: [ View ]
15th May 2014, 03:42 PM   |  #8  
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Sorry, the latest version:

Overview, an untouched screen should have all light gray lines of some kind,
a touched screen should have thick black lines near the point.
  • Thin light gray line - normal, open pathway
  • Thick dashed light gray line - maxed LED drive, open pathway
  • Thick black line - normal, blocked pathway
  • Thick dashed black line - maxed LED drive, blocked pathway
  • Thick long dashed black line - maxed LED drive, zero signal

This would all be easier if I could just use colors!
Well, I could, but you'd need to take a screenshot to see them.
Attached Thumbnails
Click image for larger version

Name:	touch.png
Views:	24
Size:	26.8 KB
ID:	2745112  
Last edited by Renate NST; 17th May 2014 at 03:43 PM.
15th May 2014, 05:16 PM   |  #9  
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Quote:
Originally Posted by Renate NST

  • Thin light gray line - normal, open pathway
  • Thick dashed light gray line - maxed LED drive, open pathway
  • Thick black line - normal, blocked pathway
  • Thick dashed black line - maxed LED drive, blocked pathway
  • Thick long dashed black line - maxed LED drive, zero signal

HI Renate!

I just ran your latest version and yes, I do have a couple of "<"-shaped thick dashed black lines in the middle of the screen and one thick gray dashed line at the very top of the screen. All the rest is thin light gray.

I'm gonna take a screenshot of it as soon as I get around installing QtADB (and the SDK) on my netbook I am currently using while travelling.

I just noticed that if I rub quite hard my unresponsive keyboard (for 10/15 seconds), the letters start to work properly again, until I keep the keyboard open. When I close and re-open it, I need to rub the keyboard again for a few seconds to get it to work again.
This also applies to any other area of the screen (buttons/icons) that does not work properly.
Needless to say, this behaviour is quite random.

Any idea about the cause and the remedy?

Marco
Last edited by marcoNST; 15th May 2014 at 05:29 PM. Reason: adding extra info
17th May 2014, 05:35 AM   |  #10  
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Snapshot of my nook attached.
Attached Thumbnails
Click image for larger version

Name:	touch-screenshot.png
Views:	19
Size:	44.0 KB
ID:	2747975  

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